ABSTRACT: Wheeler, G. A. 2005. A new species of Uncinia
(Cyperaceae) from the New World and the first report of U. chilensis
from Argentina. Darwiniana 43(1-4): 268-276.

A new species of Uncinia (Cyperaceae), U. austroamericana, is
described and illustrated from austral South America and from the
Tristan da Cunha archipelago in the south-Atlantic Ocean. This species
grows in persistently wet, base-poor sites, particularly in Sphagnum
bogs, and is known from southern Patagonia, Tierra del Fuego, and from
the largest island of the Tristan da Cunha group. It differs both
morphologically and ecologically from the similar-appearing U.
macrolepis, a minerotrophic species best known from moist depressions in
grasslands. The new species differs morphologically from U. macrolepis
by possessing achenes that, when mature, are pale-colored and
conspicuously-thickened at the apex and, also, by having more or less
loosely-flowered spikes that frequently exceed 2 cm in length.
Additionally, U. chilensis is reported for the first time from
Argentina.

The genus Uncinia Pers. (Cyperaceae) is represented in South
America with approximately 25 species (Wheeler & Goetghebeur, 1997),
at least five of which occur in southern Patagonia and Tierra del Fuego
(e.g., Barros, 1969; Wheeler, 1994; Guaglianone, 1996). In this paper a
new species of Uncinia, U. austroamericana, is described from austral
South America and from the Tristan da Cunha archipelago. In prior
reports (e.g., Marticorena & Quezada, 1985; Wheeler, 1994, 1995;
Guaglianone, 1996) these plants were referred to U. macrolepis Decne.
Salient differences between U. austroamericana and U. macrolepis are
given in Table 1. In addition, U. chilensis G. A. Wheeler, previously
known from Chile (Wheeler, 1997), is here reported for the first time
from Argentina.

BRIEF HISTORICAL OUTLINE

Kukenthal (1909) reported Uncinia macrolepis from Patagonia and New
Zealand, though the New Zealand plants are now referred to U. sinclairii
Boott (Hamlin, 1959; Moore & Edgar, 1970). Subsequently, Steyermark
(1951) described U. meridensis Steyerm. from Venezuela, and Philcox
(1961) described U. smithii Philcox from the south-Atlantic island of
South Georgia. After studying two Uncinia specimens from Tristan da
Cunha, Hooper (1968:7) assigned them to U. meridensis, and reduced U.
smithii to synonymy. More recently, Wheeler (1995) considered both U.
meridensis and U. smithii to be conspecific with U. macrolepis, whose
type collection (Hombron & Jacquinot s.n. [holotype: P]) comes from
"Magallanes" in southern South America and whose name has
priority. At that time, the species was considered to have a South
American distribution in southern Patagonia and Tierra del Fuego (e.g.,
Kukenthal, 1909; Barros, 1969; Wheeler, 1994, 1995), Bolivia (Wheeler
& Goetghebeur, 1997), Colombia (Wheeler, 1996), Ecuador (Wheeler
& Goetghebeur, 1997), Venezuela (Steyermark, 1951) and an Atlantic
insular distribution on South Georgia (Philcox, 1961; Wheeler, 1994) and
Tristan da Cunha (Hooper, 1968; Wheeler, 1995).

DISCUSSION AND CONCLUSIONS

While examining South American Caricoideae from Sphagnum-dominated
wetlands (e.g., Wheeler & Guaglianone, 2003), the author took the
opportunity to study more closely Uncinia species common to Sphagnum
bogs in austral South America. The work discussed below was initiated
due to subtle, yet seemingly consistent, differences observed between
similar-appearing bog plants and grassland plants, all of which were
then referred to U. macrolepis (Wheeler, 1994, 1995).

One of the chief diagnostic features of bog plants is the
pale-colored, conspicuously-thickened apex of the mature achenes, a
feature poorly developed (if at all) in mature achenes of grassland
plants. Also, the perigynia of bog plants are, in general, longer and
narrower than those of grassland plants; additionally, the perigynia of
the former are smooth except sometimes sparingly hispidulous just
beneath the beak, whereas those of the latter are distinctly appressed
hispid above the middle of the perigynium. It is also noteworthy that
bog plants have more or less loosely-flowered spikes that frequently
exceed 2 cm in length, whereas grassland plants have tightly-flowered
spikes 2 cm long or less. Indeed, during the course of this study, all
examined macrolepis-like plants that possessed spikes longer than 2 cm
were assignable to the new species. Issued as a caveat, however,
herbarium specimens with immature plants bearing spikes 2 cm long or
less can be difficult to place, particularly if habitat information is
lacking. Other salient differences between bog and grassland plants are
given in Table 1 and in the dichotomous key provided further below.

The present study shows that the two similar-appearing,
macrolepis-like plants differ both morphologically and ecologically.
Significantly, the plants growing in grasslands are essentially
identical to the holotype of U. macrolepis. As such, the heretofore
undescribed bog entity is newly described and named immediately below.

Morphological differences and niche requirements of the two
macrolepis-like uncinias, as propounded throughout this paper, such as
in Table 1 and in the key, seem to justify species rank for U.
austroamericana. The epithet refers to austral South America as
apparently being the center of distribution of this species. Based on
features of its perigynia and stamens, the new species belongs in
section Uncinia.

Uncinia austroamericana (Fig. 1, A-G) grows in persistently wet,
base-poor sites and is more or less confined to the southern and western
portions of Patagonia and Tierra del Fuego (Fig. 2), where heavy
rainfall and cool temperatures are conducive to the accumulation of peat
deposits. It often occurs in boggy and swampy places, particularly where
Sphagnum hummocks are well developed.

[FIGURE 2 OMITTED]

The majority of collections come from "Donatia-Marsippospermum
bogs," where typical species are, among many others, Donatia
fascicularis J. R. Forst. & G. Forst., Empetrum rubrum Vahl ex
Willd., Marsippospermum grandiflorum (L.f.) Hook. f., Carex
camptoglochin V. I. Krecz., C. magellanica Lam., as well as Sphagnum
spp. and other hydric mosses. As treated here, Uncinia austroamericana
also occurs as a disjunct on the Tristan da Cunha archipelago, where it
grows on the largest island in Empetrum bogs (Hooper, 1968).

In austral South America, U. austroamericana grows at elevations
from near sea level to about 600 m, and mature perigynia have been
collected from January through March. The quasi-linear, east-west
distribution of collection sites for this species near 52[degrees]S.
lat. in western Chile, as shown in Fig. 2, is the result of a transect
study conducted in 1976-1977 (Boelcke et al., 1985). That comprehensive
study seems to indicate that this species is more common in
southwestern Chile than present collections suggest.

As pointed out earlier, Uncinia macrolepis differs ecologically as
well as morphologically from U. austroamericana. In austral South
America (Fig. 2), U. macrolepis grows in moist to wet depressions in
grasslands, particularly those dominated by Festuca gracillima Hook. f.,
but has also been recorded from subalpine meadows and dry heathlands. On
the subantarctic island of South Georgia (Philcox, 1961) this species
occurs in Festuca grasslands and on rock-laden, grassy hillsides. In
northern South America, on the other hand, Uncinia macrolepis grows
primarily on wet rocks and among cushion plants in paramo (Steyermark,
1951; Wheeler & Goetghebeur, 1997), though seemingly in sites where
Sphagnum hummocks are absent or poorly-developed. Plants of U.
macrolepis, including the holotype, are illustrated in Wheeler
(1995:163, Figs. 1-4) and Wheeler & Goetghebeur (1997:12, Figs. 1,
2).

Specimens of U. macrolepis examined from the southern half of South
America (see Fig. 1, H-I) and South Georgia are cited below; specimens
from northern South America are cited elsewhere for Colombia (Wheeler,
1996), Ecuador (Wheeler & Goetghebeur, 1997), and Venezuela
(Steyermark, 1951). Regarding the geography of U. austroamericana and U.
macrolepis, the markedly discontinuous distributions of both species are
probably best explained, in each case, by the exogenous transport of
desmochores (hooked fruits), with long-range dispersal taking place by
bird migration.

Uncinia chilensis was originally reported from Chile (Wheeler,
1997) and this note represents the first report of it from Argentina. In
Argentina it is known, thus far, only from a single locality in Rio
Negro Province, where it was collected in a forested area. In Chile,
where the plant grows from about 1000 to 1500 m s.m., it is known from a
single locality each in Arauco, Bio Bio, and Concepcion provinces (VIII
Region, Bio Bio), and from one in Malleco Province (IX Region,
Araucania). Mature fruit has been collected from December through
February. The plant is illustrated in Wheeler (1997:4, Figs. 2, 3).

This species is somewhat similar to U. erinacea (Cav.) Pers. but
differs by having: long-awned pistillate scales; lanceolate, short-awned
staminate scales; larger perigynia, achenes, and rachillae; staminal
filaments narrower than the anthers; and leaves (abaxial side)
papillate-scabrescent (Wheeler, 1997). Because U. chilensis is poorly
represented in major herbaria, it is probably uncommon in both Argentina
and Chile.

The author wants to thank E. R. Guaglianone (Instituto de Botanica
Darwinion, Argentina) and S. Beck Herbario Nacional de Bolivia) for
duplicate specimens of Uncinia; the Darwiniana Editorial Board, R.
Pozner, and an anonymous reviewer for manuscript suggestions and
skillful editing, and for a spanish abstract; A. Cholewa (University of
Minnesota) for arranging loans and other herbarium services; and also to
the directors and curators of the following herbaria for the loan of
specimens: A, BM, GH, HIP, LPB, MIN, NA, P, RNG, and SI.